Draft regulator for orchard heaters



Dec. 30, 1941. J. R. CAMPBELL 2,268,067 DRAFT REGULATOR FOR vORCHARDHEATERS l IFiled 0G12. 17, 1938 :5V sheets-sheet i p 'j 1 W UA1/504'Janis 1. CAMpaELL Dc."30, 1941. 1 R CAMPBELL 2,268,067

DRAFT REGULATOR FOR ORCHARD HEATERS V v-Filgel oct. 17, 1938 ssrheetsheet 2 I 3x1/UWM Juf/5.5 CAMPBELL Dec. 30, 1941. L4 R CAMPBELL2,268,067

DRAFT REGULATOR FOR ORCHARD HEATERS Filed Oct. 1'7. 1938 3 Sheets-SheetPatented Dec. 30, 1941 `DRAFT REGULATOR FOR ORCHARD HEATERs JamesCampbell, Ontario, Calif., `assigner to` William C. Scheu, Upland,Calif.

Application October 17,` 1938, Serial No. 235,299

8 Claims. (Cl. 158-91) This invention relates to `temperature-controlleddraft regulators for liquid fuel orchard heaters and is concernedparticularly with heatresponsive devices for automatically establishinga controlled influx ofcombustion air to the fuel vaporizing chamber ofsuch a heater for` normal burning operation thereof following thestarting or ignition period of such a heater.

`The heat-responsive draft-regulating device of this invention isprimarily adapted for use with vaporizing type liquid fuel orchardheaters. In `heaters of this type a vaporizing name is maintained at'ornear the surface of the body of fuel contained in the heater to causevaporization from the surface of this fuel. The oil vapors pass upwardlyinto a stack where additional air is mixed with them to causesubstantially complete combustion of the vapors in a main flame at apoint removed from the vaporizing fiame. A heater of this general typeprovided with such a stack forming a main combustion chamber is shown inU. S. Patent No. 1,930,863, issued October 17, 1933, to William C.Scheu.`

Heaters of this type are provided with one or more air-admittingOpenings in the body communicating with the vaporizing chamber to admitair to the vaporizing flame in the vaporizing chamber. With suchIarrangement it is preferablel to supply a relatively large quantity ofair to the vaporizing chamber to support the vaporizing flame when theheater is first ignited and until the vaporizing chamber has beenheated. After the vaporizing chamber has become heated and the maincombustion flameis Wellestablished, a smaller amount of heat from thevaporizing flame is required to vaporize fuel; and if the `air supply isnot reduced to diminish the flame, there will be a tendency to vaporizean excess quantity of fuel. These relations are all aiunction of theheat generated in the vaporizing chamber and are substantiallyindependent of `the temperatures existing Where the main combustiontakes place in the stack, or at any other place removed from thevaporizing iiame.

In order to obtain proper and satisfactory Op; eration `of such a liquidfuel heater it is desirable to restrict the flow of air admitted to theVaporizing chamber after a sucient quantity of heat has been generatedtherein. In many cases this operation is performed manually or not `atall due to the labor involved. When this operation is not performed theheater consumes an excess quantity of` fuel and often smokes badly, thuswasting fuel. l

The principal object of the invention is to provide a heat-controlleddraft-regulating device for use in connection with a vaporizing type ofliquid fuel orchard heater, which is operable to provide a substantiallyunrestricted inflow of lair into the vaporizing chamber during apreliminary ignition period and `to restrict automatically the'admission of air to said vaporizing chamber When the ignition iscompleted, in response to a temperature increase resulting from the heatgenerated within the vaporizing chamber of the heater, so as tothereafter maintain the relatively restricted admission of air to thechamber in quantities suicient to maintain the desired normal burningrate during subsequent operation of the heater.

A further object of theinvention is to provvide a heat-responsivedraft-regulating device for use in association with a vaporizing typeliquid fuel orchard heater, Which is rugged, simple in operation andconstruction, and which may be readily removed for repair or fortransfer to another heater where it may be readily installed.

Further objects and advantages of the invention, of which the above aretypical, will become apparent as the description proceeds.

The `draft-regulating device of `my invention maycomprise a pivotallymounted regulating plate which is disposed adjacent an air-admittingopening communicating With the vaporizing chamber of a liquid fuelorchard heater in which a vaporizing flame is maintained Within theheater at a place removed from the main flame. 'I'he'draft-regulatingplate is movable between a. first position which `provides the maximumaccess of air to the vaporizing chamber through the air-admittingopening and a second position restricting the passage of air through theairadmitting opening. The draft-regulating plate is biased toward thesecond position in which the-passage of air through the Opening isrestricted. Thermostatic means, such as la bimetallic element, isdisposed in heat-receiving relation to the 'vaporizing flame in theheater and is adapted to hold the plate in therst position andvisoperable in response to the heat generated by the vaporizing` flame inthe vaporizing chamber to release the plate and permit the plate to moveinto the second position.`

It is highly desirable `that the device operate in such manner as nottoout off completely the air admitted to the vaporizing chamber. Thismay be accomplished by shaping the regulating plate so that it does notconform to and does not cover the entire air opening. Or it may beaccomplished by providing limiting means, either fixed or movable foradjustment, that limits the movement of the plate toward the secondposition to a position at which the opening is not entirely closed-andthe passage of air is restricted but not stopped, or both of the abovemeans may be used to accomplish this object.

How the-above, as Well as other objects and advantages of my inventionare attained will be more readily understood by reference to thefollowing description, and the annexed drawings, in which:

Fig. 1 is a fragmentary vertical section through the base of avaporizing type orchard'heater provided with the draft-regulating deviceof my invention, the draft-regulating plate being shown y in an open orsubstantially non-restricting position;`

Fig..2 is a fragmentary plan view of the draftregulating device takenfrom above on line 2 2 ofii'g. 1;V n

n VFig". 3 is an enlarged fragmentary vertical section through thedraft-regulating devicein the aspect of Fig. 1, showing thedraft-regulating plate in Va closed or Aair-restricting position;

n Fig. 4 is an inverted plan View of the draftregulating device taken online 4-4 of Fig. 3, with the insulating cover over the bimetallicelement removed;

Fig. 5 `is a view similar to Fig. 4 of the draftregulating device alone,except that the insulating cover of the bimetallic strip is in vplaceand the draft-regulating plate is shown in an open position;

Fig. 6 is a vertical section through the draftregula'ting device on line6-6 of Fig. 3;

l Fig; 'l is a plan view of a draft-regulating device'showing avariational form of draft-regulating plate;

Fig. 8 is a vertical section through Fig. 7, partially in elevation,showingthe variational form of lplate in cross-section; and

y Figs. 9 and 10 are views similar respectively to Figs. Vv'l vand 8,showing another variational form of draft-regulating plate.`

There is shown in Figs. 1. to 3 of the drawings a portion'of a standardtype of vaporizing liquid fuelorcha'rd heater, indicated generally atI0. The orchard heater -comprises a bowlA II which not onlyA provides abase for supporting the upper structure but also forms a reservoir thatcontains a body'offliquid fuel I2 which is vaporized in bowl "I I andburned in the heater stack. Bowl` II is provided with a cover I4 whichhas a centrally disposed collar portion Ida/around which the lower endof stack 4I5 lits snugly. The stack may be of .any type suitable fororchard heaters, the exact kind being immaterial as far as the presentinvention is concerned.

. rLIT-he space I 6 above the fuel body I2 and enclosed by the walls ofbowl II and cover I4 constitutes a vaporizing chamber.- A suitableopening defined by the raised collar portion II of cover .Ill` isprovided in order to admit air to the vaporizing chamber for maintenanceof the vaporizing'ilame therein. The collar portion II also forms amounting means for the draft-regulating device described later. A drafttube or flame-stabilizing rbaille I8`is preferably provided tofacilitate the maintenance of a vaporizing flame within chamberV IG. Theupper end of draft tube I8 is preferablynprovided with an outwardlyextending flange which engages the inwardly turned flange on raisedcollar Il as shown to support the draft tube, which extends downwardlyfrom the wall of cover I4 into the oil body I2 as illustrated in Fig. l.The upper end of draft tube I8 is open for the admission of air whichenters the vaporizing chamber through the draft tube. A suitable wick I9is preferably provided adjacent the upper end of tube I8, the wickmember taking any suitable form, such as the body indicated, and ispreferably of fibrous asbestos or other porous material. The wick ispreferably wrapped or'enclosed in a foraminous metal envelope 2i! whichholds the wick in place and yet permits `access of oil to the lowerportion of the wick.

As may be seen best from Fig. 3, draft tube I8 is provided with anopening 22 just beneath the top flange at the lower or left-hand side asviewed in Fig. 3. A short lug 23 projects inwardly through opening 22from the rim of `collar il. This construction not only assures that thedraft tube will be inserted through collar II and maintained in theproper position, but the lug also locks the dra-ft tube to cover I4against accidental removal.

The draft-regulating device indicated generally at 25 comprises body 26`having an air-admitting opening 2l, a draft-regulating plate 28pivotally mounted adjacent opening 2'I and adapted to control the flow of air through the opening, and a bimetallic thermostatic elementl 3,9enclosed within an insulating housing 3| and adapted to effect closureof the draft-regulating plate. Body 26 is of circular outline and has adepressed central portion which is of proper diameter to tsnugly Withinthe open upper end of draft tube i8. The vertical wall portion ofv thebody formedl by the` central depression is indented at 32 to receive lug23 (see Figs. 4 and 5); A similar indentation 33, is made in the bodyopposite indentation 3 2, the indentation 3-3 receiving the folded seamin draft tube I 8. The twoV indentations 32 and 33 being of a differentsize l and shape, `itis possible to insert body 26 into the upper end ofdraft tube I-in only one position.y This construction has the advantageVthat the draft-regulatingdevice isalways held in the proper position,and the devices in all the heaters are in the same position, theuniformity of position malringlfor simplicity and certainty in operationby unskilled labor of the large number of heaters required in anorchard.

The air-admitting opening 21 is placed in the generally horizontalcentral plate-like portion 26a. of body 2t, and is preferablysemi-circular in shape as shown in Figs. 2 and 4. The flow of airthrough Aopening 21 into the upper end of draft tube I8 and thence intochamber I6 is regulated-by draft-regulating plate 28 which is alsogenerally semi-circular in outline and is shown as `having a recess ornotch 41 located.V

28 swings, lasV may be seen from a comparison of Figs. 1 and 3.

The thermostatic Vcontrol means comprises` a coiled` bimetallic element-3which is attached in any suitable manner at one end to bracket-,31.

Bracket 3'I-is attached to plate-26a by any suit-` able means, as byrivets andisfpreferably heatk lWhile.` it` is not necessary that shank43 insulated from direct engagement with` theplate.

`by a layer of insulation 38, asseen best in Fig. 6,

to retard the rate `of heat'transfer tothe thermostat. Bimetal strip 38`curves through almost one complete turn or circle when it iscold, and`1 roccupies a position shown in Fig. 5. In this po- `sition,1it isengaged by a holding member in the form `of curved arm 4I)` which isattached to the `underside of plate 28 and projects downwardly therefrom`in such a manner that the` end `of arm 48 bearsagainst the side ofbimetallic element138. Engagement of arm 48, which constitutesadownwardly projecting portion of lplate 28, with `the bimetallic elementholds plate L28 `raised in the upwardly tilted position illustrated inFig. l. 1

ingflame within vaporizing chamber I6, .bimetallic` element 38straightens out somewhat and reaches a position similar to thatillustrated in `material 49, such as asbestos or the like,

in chamber IIS.` For this reason, the interior walls of housing 3ll arelined with a layer of insulating It is preferable to extend the toplayer of insulation 38 entirely across the interior of housing 3l, as

` shown in Fig. 6. To facilitate this, plate 26a is j a In` response toheat generated by the vaporiz` i preferably` provided with a pair ofelongated bosses 48 which space thelayer of insulation 38 from the underside of plate 26a sufciently `that it clears cam 42 andpasses just abovebimetallic element 38. I a I The operation of my improveddraft-regulating device `will now be described briefly. Assuming thereservoir to have been filled with a body of `liquid fuel I2 to theproper level, the

heater is now ready `to be` lighted. To accomplish this, an attendantfirst raises Vthe outer` edgerof draft-regulator plate 28 and swings theFig. 4 in which the arm 48 no longer engages l the bimetallic element.When arm 48 disengages e `the bimetallic elementnplate` `28 dropssuddenlyg a e under the influence of 'gravity to a lowered posi- -tionsuch as shown in Figs. 3 and 4. In the extreme lowered position, theedge` of plate 28 lies against the portion lof body plate 26a whichforms a margin around opening 21, because the dimensions of plate 28 areslightly larger than those of opening` 21. However, under somecircumstances it may beidesired that` plate 28be not allowed tor-eachthis extreme lowered position, but that its downward movement belimited toa position such as is shown `in Fig. 3 in which the plate isnot entirely closed. For this purpose, some `typeof I shank so that thecam can be rotated about the ,shank axis into adjusted positions` by`turning plate clockwise about its hinge until the plate passes top deadcenterand rests against the top ofshaft 43, which acts as a stop to holdthe :plate in this open position, `as shown by dotted lines in Fig.` l.The attendant then inserts theetip of hislighting torch in opening 21and discharges a suitable quantity of a burning ignition fluid,

lwhich may comprise a mixture `of gasoline and kerosene or the like,through opening 2 1` onto wick` I8. A portion of this burning uid fallsdo-wn upon the` surface` of` fuel body I2. The

`ignition iiuid,` burningon the surface of `fuel body I2. and aroundwick I9, establishes Ya vaporizing flame which heats the liquid fuelsufficiently `to effect generation ofL fuel vapor therefrom, and

, this vaporiscarried into the stack I by the draft element 38 in themanner shown in Fig. 5.

thegshank, but the shape of the shank makes it possible to turn it bymeans of` a detachable key or wrench of the proper size. Theoutline ofcam 42 may be aspiral or eccentric curve or other outline of `varyingradius about the axis of cam rotation. Lever `45, having one endflatthrough shank 43 and bears against the flat end `of leverr45to holdshaft 43 `against dropping downwardly through plate 26a. l a

be square, it is preferred that 1it be some shape other `than round, in`order `that the cam and hand lever 45 may be non-rotatably affixed tothe shankand that the` lattermay `be turned "bya detachable key. If akeyor the like is not used, lever45 may be usedito rotate shank 43 inadjusting the positionof cam 42; and if a key` is used, lever 45 servesas visual means to indicate the position of ca1n42.`

Bimetallic element 38 and cam 42 are prefername `andlthus properly delaythe responsey of the thermostat to heat receivedl from" the flamethrough the vaporizing chamber.` When the rate of `evolutionof fuelvaporsis adequate, the main combustion flame of the heater isestablished within or above the stack assembly I5, and

it will beV understood` that some ignition fluid mayibe poured into thestack to facilitate ignition of the fuel vapors withinthe stack.

After the tip o-f` the lighting torch is removed from opening` 21,.,plate 28 is` manually rotated counter-clockwiseto the fullline positionof Fig.

1 in `which arm 48 engages the side of bimetallic In this first orinitial operating position, regulating plate 28 is raised above bodyplate 26a and allows maximum passage` of air through opening 21Draft-regulating plate 28 is gravity biased in the rst positiontoward aclosed position and is held in this first position, `by engagement ofarm 48 with bimetallic element 38, `against gravity which tends to movethe plate counter-clockwise into alsecond or closed position in whichthepassage of air through opening 211 is more or less restricted. Allthe time that the regulating plate is held in this first position, arelatively large amount of air is admitted to vaporizing chamber I6` andthe vaporizing flame maintained therein burns at a relatively highrate.The heat from thisvaporizingflame is transmitted to bimetallic element38 by conduction and radiation from the `metal parts ofthe draft tubeand regulating device, and in response to this heatreceived thermostat38 tends to straighten out. The curvature of the thermostat ispreferably such that all movement of thefree end of the thermostat issubstantially at right angles to the path of movement of plate 28 andarm 48 and consequently the straightening movement of the A* thermostat,while engaging arm 48, causes'substantially no movement of arm 40 thatraises or heat `received. by .bimetallic element 30 is such that thefree end of the thermostat element movespast and disengages the end ofarm 40, reaching some such position as shown in Fig. 4. As the free endof bimetal 'strip 30 moves past the end of arm 40 out of engagement withthe arm, plate 28 drops under the influence ofv grav- -ityy toits secondoperating position in which the flow of air through opening 21 isrestricted to a greater or lesser extent accordingto the amount ofclosure permitted plate 28.`

The position of draft'plate 28 rin its second or air-restrictingposition is' determined in general bythe position of cam 42. If'carn 42is turned in av-counter-clockwise direction as viewed in Figs. 4 and 5for approximately one-fourth revolution, then'a portion of the involutecam of relaplate r28 is allowed to. drop until it comes into contactwith plate 26a, which limits further movement of the plate. point ofmaximum closure; Abut even then the Plate 28 is now at itsv draft platehas been released by thermostat 30 inresponse to heat received from theVaporizing flame.

The rate of heat transferred to thermostat 30, r Adepends upon thequantity and efficiency `of theV insulating means '38 and46 withinhousing 3l; and-the period of time required for the thermo- 'stat torelease plate 28 maybe increased or `decreased,respectively byrincreasing or decreas- Atively small radius is turned opposite arm 40and opening 2T is notentirely 'closed because therel cess or indentation41 in the edge lof plate '218 con- Atinues'topermit a certain amount of'air to pass through opening 21 and reach the vaporizing flame. V,Thevaporizing flame is reduced in size and ability to vaporize fuel as aconsequence of its reduced air supply, and under-these condiv `tions themain vaporizing flame in stack l5 is y also reduced to a minimum.

When cam 42 is in the position of Fig. 4, the

i edge of yarm 4ll engages the edge of cam 42 when draft plate 28 hasdropped to the position of Fig. 3, and before the point of maximumclosure of the 4plate has been reached. In this position, less`restriction is afforded on the amount of i air passing through opening21 vthan under the conditions previously described, because there isspace between plates 28 and 26a through which air may pass to reach,opening `2l. This opening is in additionl to the opening afforded by therecess 41 inthe edge of plate 28. As a consequence ofthe somewhatincreased air supply to thevaporizing flame, more fuel will be Vaporized'and the *mainv combustion :flame will burn higher.

A still higher fire in sta-ck l5 may be secured by rotating cam 42 in aclockwise direction as viewed in Fig. 4, any desired amount up to apbyextinguishing' the vaporizing name, thermostat 30 cools and tends toreturn toits initial po `ing ,31 to permit .cam 42 and arm ing theamount of insulation within the housing. The insulation preferablyentirely surrounds the bimetal strip, or substantially so. For anyparticular type of heater, the correct amount of insulationmay bedetermined by experiment, land should be made such that the maximumamount of air is admitted to the vaporizing name for a sufficient timeto insure an adequate heating of the fuel body and the generation of an"adequatel amount of fuel vapor within chamber I6..V LT-shaped slot iscut in oneside of hous- `49 to operate through the housing wall.

Afterv the re in the heater has been put out sition as shown in Fig. 5.However, as will be seen from Fig. 4, the bimetallic element cannotproximate-ly a quarter revolution. In its new po- Y sition, the portionof cam 42 opposite arm 4.0 'l

isof greater radius and engages the edge of arm 40 -when plate 28 is ina higher position than in Fig.` 3. Consequently, the gap between platesY28 and 26a is increased and a still greater amount of airis allowed toenter through .opening 121,

the increased amount of air causing the Vaporizing flame to burn higherthan under the vconditions previously described.

From this .discussion it will be seen thatthe secondr operating positioninto which the draftregulating platefalls under the influence of`gravity after arm 40 has become disengaged from bimetallic element 30,may be varied somewhat with respect 'to plate 26a by a limiting means,

' such as cam 42. VIn this second position of draftregulating plate 28,the quantity of air liowing throughl opening 2l is restricted to agreater or lesser extent accordingly as plate'ZB is'nearer or n fartherfrom plate 26a, and the burning rate of the vaporizing flameisfcontrolled by the quantity of air admitted. But in any event, the airadmitted through opening 21 is less than that admitted whenthedraftplate is in vits original position'for admission of the maximumamount kof `air tothe newly lighted flame and 'before the do this sinceits free end now comes into contact with the side of arm 40. gagement,continued cooling of thebimetallic element does not change .its positionbut merely causes it to press lightly against the side of arm 48; andbecause of the circular shape of the'ther- .mostat no damage is done toit since the pressureV vis not sufficient to cause any permanentdeforma- `tion of the bimetallic element. Thev parts remain inthisposition until itY is desiredto lagain light the heater, at which timedraftplate 28 is lifted as previously described; and-the act of liftingYthe draft plate removes arm 4! from engagement l with thermostat 30which latter can then spring .back to its normal position when cold,that is,`

the position shown in Fig. 5. When the draft- .regulating plate is againlowered to its initial operating position, arm 4El'comes into contactwith the/side of .thermostat 30, and the draft-regulat- `ing device isreset to repeat the cycle of operations` previously described. Recess4,7 serves as a finger hole to grip the plate and lift it.

`The coiled shape of thermostat 2li is of definite advantage inpreventing injury to this element.Y

nent deformation ofthe thermostat which would K impair its operation. VAdditional safeguard against injury of the rparts is provided by Wirehinge 35. If draft plate 28, when in a lowered' or air-restrictingposition and in` engagement Iwith cam 42, as shown inFig. 3, is forceddown- `wardly, hinge 35 simple bows slightly and permits the draft plateto rock about its point of engagement with the limiting cam until theplate comes in contact with body plate 26a. As soon` as pressure ontheplate is released, the hinge springs the plate black to its properposition.

' The'plate is preferably attached to Wire 35 near the mid-point of thelatter to obtain the full After this ent be given tothe draft-regulatingplate;

benefit of the resilient character of the hinge.` Spring hinge 35 ispreferably made of some material that will not lose its resilientcharacteristicsfafter being repeatedly subjected to relatively hightemperatures.

It is preferable, though not necessary, that draftplate 28 be so shapedasto never fully cut off the flow of air through opening 21 but becapable only of imposing restriction upon the air flow up to somepredetermined maximumextent. In the form of the invention previouslydescribed, this lwas accomplished by providing notch 41 at the edge ofplate 28 which left a portion of the opening `21 permanently uncovered.variational forms of the draft-regulating plate which accomplisn lthissame object, are shown in Figs. 7 to 10 inclusive, from which it will beseen that Stillother shapes of the draft plate may be employed withinthe scope of my invention. f In Figs, '7 and 8 there is shown adraft-regulating plate 28al of whichthe curved margin has beenturnedupwardlywat right angles to the main portion of the plate to form anupturned flange 50. The flange ishighest` at `its center oppositeindentation 32 and tapers away in either direction from that point totheface` of the plate. -The upturned fiange 50 not only provides aprojection .by which the draft plate may bellifted after it has droppedinto lowered posil.

tion, but it also leaves a `crescent-shaped portion 5| "of opening 21which is not covered by the draft plate and so remainsopen to admit aireven when the draft-regulating plate is` in its position of maximumrestriction of air flow.

Draft plate 28h in Figs. 9 and l0 ,illustrates another modification ofthe forms which may In this form, a sector of the plate is turnedupwardly along a line representing a chord parallel to hinge 35. `Flange53 formedinthis manner provides a convenient projection for graspingtheplate when it is desired to lift it from the closed position andmanually reset the device for further operation. The turned-up portionof plate 28h forming flange 53 leaves a sector-shaped opening 54 whenthe draft plate is fully` closed as shown in Figs. 9 and l0, andthissector-shaped opening 54, which is a` portion of air-admitting opening21, remains permanently uncovered by thedraft plate to admit air evenwhen the draft plate is in its position of maximum air restriction. l

In all other features of construction and operation the modifications ofmy invention illus` trated in Figs. 1 to 10 inclusive `are the same ashave been `previously disclosed in connection with the description ofFigs. 1 to 6.

Having described a preferred embodiment of than limitative upon, theinvention set forth in l the appended claims.

I claim:

1. In association with a vaporizing type liquid fuel orchard heaterprovided with a vaporizing chamber having an air-admitting opening formaintaining a vaporizing flame within said heater at a place removedfrom the main flame, a heat-responsive draft-regulating device whichcomprises: a pivotally mounted regulating plate a said thermostaticmeans comprising a bimetallic element engaging the projecting arm tohold the -plate in the first position, and operable in response to `heatgenerated by said vaporizing ame "to release the plate and permit theplate to move into said second position; and a rotatably adjustable cammember engaged by the projecting arm as a result ofsaid movement of theplate to limit the restriction imposed by the plate on passage of airthrough `the opening.`

" 2. A heat-responsive draft-regulating device for an orchard heater,`Whichlcomprises: a body member having an air opening; a draft-regulatingplate pivotally mounted on the body adjacent said opening jand movablebetween a first position` affording relatively free passage of air`through the opening and a second `position restrictingpassage of airthrough the opening, said plate being biased toward the second position;and thermostatic means engaging the plate, said `thermostaticmeanscomprising a coiled bimetallic elementcurved in a plane at rightangle to the plane of movement ofthe plate that is adapted to hold theplate in the first position and is operable `in response to heatgenerated within the heater to release the plate andpermit the nomovement of the plate while engaging the*v latter. Y

i 3. A heat-responsive draft-regulating device l for an orchardheaterLwliich comprises: a body member having an air opening; adraft-regulating vplate pivotally mounted onV the body adjacent saidopening and movable betweenl a first position affording relatively free`passage `of air through the opening and a second position re`jlsttricting passage of air through the opening,

said plate being biased toward the second position; thermostatic meansengaging the plate, said thermostatic means comprising a coiledbimetallic element curved ina planeperpendicular toA i. the planeofmovement ofthe plate that is adapted` to hold the plate inthe firstposition and isA operable in responseto heat generated within the heaterto release `the plate and permit the plate tov move into the secondposition; andheat insulating meansl substantially entirely `surroundingthe bimetallic element toretard the transfer of heat to andfrom thebimetallic element.

4. A heat-responsive draft-regulating device for an orchard heater,which comp-rises: a body member having an air opening; adraft-regulating plate pivotally mounted on the body adjacent saidopening and movable between a first position affording relatively freepassage of air through the opening and a second position restrictingpassage of air through the opening, said plate being biased toward thesecond position and having a. downwardly projecting arm;` andthermostatic means engaging the plate, said thermostatic meanscomprising a coiled 4bimetal- 75 lic element curved in a plane at rightangles to through the opening the planeof movement ofthe plate thatis'radapt'- ed to hold'the' plate inthe rstposition and is operable inyresponse to heat generated within the yheater to releasethe Vplate andpermit the plateA to move into the second position; and a l plate-likemember adjustably mounted on and beneath thebody in a position to engagethe projecting arm as a result of downward movement of the plate tolimitthe restriction imposed bythe plate onthepassage of 'air throughthe-opening. v v y f 5. Av y heat-responsive draft-regulating .deviceforan orchard heater, which comprises: a body member shaving anr airopening; a draft-regulating plate pivotally mounted on the body adjacentsaid opening and movable between a first position affording relativelyfree passage of air throughvthe opening and-a second positionrestricting passage of yair `through the opening,

said plate vbeing biased to-wardthe second position; thermostatic meansengaging theplate, said thermostaticxmeans comprising a bimetallioelement adapted to hold the plate, in thefirst position and operable inresponse tov heat generatedr within the heater to release theplate andpermit vthe plate tomove into the secondposition, the

ing platepivotally vmounted on the body ladjacent said opening andmovable between a rst position affording relatively free passage of airthrough the opening and a second position restricting passage of kairthrough the opening, said plate being biased toward the second position;aV holding member;

` and thermostatic means holding the plate in the rsvt.l positionbyengagement with the holding memberfand operable in response to heatgenerated within the'heater to move out of engagement "with the holdingmember and release the platerto permit the plate rto move freely intothe secondgposition, said vthermostatic' means comprising'a Acoiledbimetallic element curved in a planeet right angles kto the plane ofmovement of the plate, themovement of the bimetallic elementtat thevpoint of said engagement in response'v -tokheatV1 .being substantiallyatyrightjangles to the Qpath ofmovement of the plate and causing whenthe plate is moved to f f i v2,268,067

substantially no movement of the plate during engagement of lthebimetallic element and said holding member. f

7. A heat-responsive draft-regulating device for an orchard heater,which comprises: a body member having an air opening; a draft-regulatingplate pivotally mounted on theV body adjacent said open-ing land movablebetween a first position aifording relatively free passage of airthrough the opening and a second position restricting passage of airthrough the opening, said plate being biased toward the second position;and fixed thermostatic means mounted on the body member lto engage aportion of the movable plate and hold the plate in the first position,said thermostatic means comprising a, coiled bimetallic element having afree end that engages said plate and is movable in response to heatgenerated by the heater to disengage the plate and 4permit the plate tofall freely into the second position,` the bimetallic element being sopositioned that movement of the free end of the element at the point ofsaid engagementis substantially at right angles to the path vof movementof the plate at that point and causes substantially no movement of theplate during yen-v gagement therewith.

SQA heat-responsive draft-regulating device for an orchard heater havinga vaporizing llame within the heater, which comprises: a body memberhaving an opening admitting air to maintain the vaporizing llame; adraft-regulating plate 'pivotally mounted on'. the body adjacent saidopeningy and movable between a first position affording relatively freepassage of air through the opening Yand a second position restrictingpassage of*v air through the opening, said plate being biased toward thesecond position; a holding member; and thermostatic means disposedin'heat-receiving lrelation to the vaporizing flame and `holding theplate in the rst position by engagement with the holding member and heatoperable to move in engagement with the holding member-before reaching aposition out of engagement with the holding-member, said thermostaticmeans comprising a bimetallic element 'having a free end that engagessaid holding Y member and is movable in response to heat generated bythe vaporizing flame to disengage the holding member and permit theplate to move Vfreely into the lsecond position, the bimetallic elementbeing so positioned that movement of the free endof the element at thepoint of said engagement is in a direction that causes substantially' nomovement of the plate during said 7engagen'rent. 1 i

' JAMES R. CAMPBELL.

